Abstract: An installation for the treatment of products in bulb or tuber form in relation to the removal of the outermost layer thereof, comprising a channel through which the products can be transported between an inlet and an outlet that are at different levels, which channel is delimited by a first series of rotary treatment elements arranged alongside one another and extending transversely to the direction of transport, and by an opposing boundary opposite the series of treatment elements. The opposing boundary is determined by a second series of rotary treatment elements while the input is at a higher level than the output.